Field of the Invention
The present invention relates, in general, to lighting fixtures (luminaires) that utilize light emitting diodes (LEDs) as a light source and, more particularly, to lighting fixtures incorporating LEDs configured in a manner to amplify and direct light produced by such lighting fixtures.
Description of Related Art
Conventional lighting fixtures such as streetlights and office lights have typically utilized incandescent, halogen, or fluorescent bulbs to provide light. The use of incandescent and halogen bulbs has been problematic in a number of ways. First, incandescent light bulbs are very energy inefficient. A large percentage of the energy incandescent light bulbs consume is released as heat, rather than light. Although fluorescent bulbs are more efficient than incandescent light bulbs, fluorescent bulbs raise environmental concerns, and are still very inefficient when compared to LEDs or other similar solid state light emitters.
Additionally, incandescent and fluorescent light bulbs have short life spans when compared to solid state emitters. This requires lighting devices to be replaced more frequently. Such short life spans are particularly more problematic when used in overhead lighting in office buildings or in streetlights, where access may be difficult. Replacement is not only time consuming, but can be dangerous.
Furthermore, the unwanted heat produced in these lighting systems adds not only to additional energy costs but may also requires additional air conditioning to lower the temperature of the area lit by the system. For example, in large buildings, overhead lighting is typically provided by lights placed near the ceiling and directed downward. These buildings often require additional air conditioning to compensate for this energy produced as heat.
Although solid state emitters, such as LEDs, are known to be more energy efficient, LEDs have not been considered in the past as an option for providing quality light in many applications, such as streetlights and office lighting systems, because LEDs do not provide enough useful light at a distance. Moreover, LEDs are a new technology, and therefore are more expensive. Accordingly, extending the use of LEDs is a particularly desirable goal. More recently, high-powered LEDs have been developed, thereby providing useful light output for incorporating LEDs into lighting fixtures for use as streetlights and office lights. However, the use of LEDs in such lighting fixtures typically requires a large number of LEDs clustered closely together to provide useful light output. Accordingly, lighting fixtures incorporating LEDs in this manner generate a large amount of heat energy when the LEDs emit light. This heat energy has to be dissipated. If this heat energy is not effectively removed, the high temperature caused by the heat energy will reduce the luminance and life span of the LEDs. Therefore, each of the foregoing-described lighting fixtures requires a complex heat dissipating mechanism to adequately remove the heat energy produced by the large number of LEDs.
In view of the foregoing, a need exists for a lighting fixture for use, for example, as a streetlight or an office light that utilizes a minimal number of LEDs to produce useful light at a distance without creating excessive heat within the lighting fixture. A further need exists for an LED lighting fixture having a relatively simple heat dissipating mechanism. A need also exists for an LED lighting fixture that accomplishes amplified lighting with the use of a minimal number of LEDs.